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Mike Farmery: Hello, my name’s Mike Farmery. Today, I’m talking with Alastair Hobday, the fuel and lubricant specialist for Rolls-Royce, about some of the challenges facing the world of jet fuel. We’re in a wonderful building in the engine test. Alastair, tell us where we are today.

Alastair Hobday: Hi, Mike. Today, we’re in the preparation shop, next to our ultra-large testbeds in Derby, where we prep the engines ready for test before they go out to the customers.

MF: So, we’re going to hear a few offsite noises today, I think. Alastair, it’s been a very tough time for your customers over the last year or so, but as the recovery gets underway, what are the conversations you are having with your customers, and what are you hearing from them about some of the fuel-related challenges they’ve been facing?

AH: It’s been a huge time of challenge for the aviation industry, for our customers, and, of course, for Rolls-Royce. The two main topics really that we’re talking to customers about: one, relates to how many aircraft have been parked up for an unprecedented period of time. We’ve never had so many aircraft with our engines on the ground for so long, and clearly, returning those aircraft and engines safely to service is a big challenge – making sure that from a fuel and a fuel system perspective, those aircraft and engines are fit to fly.

The other main topic that we’re hearing an awful lot about is how the industry’s got this very positive mindset of “build back better” following COVID and all the challenges of the pandemic. Part of “build back better” is around the increased focus on sustainability, and, from a jet fuel perspective, that’s really around sustainable aviation fuel. So, that is a key topic for all our customers and something that Rolls-Royce is very focused on at the moment.

MF: Alastair, when your customers were responding to the pandemic, could you tell us some of the challenges they faced when they were putting their aircraft into storage?

AH: Clearly, management of the condition of the fuel system in the engine and the aircraft is a key part of ensuring safety and appropriate storage of the equipment. At the time of the pandemic beginning, we did have in the industry two quite significant events associated with one of the biocides that is approved for use. Those biocides limit the formation of microbial material and help to keep the aircraft systems in an appropriate manner. Because one of those biocides was no longer available, that did limit the options for the operators. So, we had to ensure, working closely with our operators and our customers, that they followed very closely the engine and airframe manuals to ensure that it was limiting the amount of water in the aircraft. They’re doing regular water drains and all the other good practices that people do, and that became more critical as there was just a lack of the appropriate biocides available in certain parts of the world.

MF: Yeah. That must have been really challenging because everybody’s trying to put their aircraft into storage at the same time. I can imagine you were bombarded with questions from airlines about how to do it safely.

AH: Indeed, and we work through our operations center, liaising with a lot of the customers to understand whether they were using a biocide, if they were using a biocide, which one, and whether any other technical challenges around following the manual as being the requirement.

MF: Has it been equally challenging for airlines to bring their aircraft back into service now the market is starting to get going again?

AH: Yeah. I think the positive message we are hearing now is that we’ve heard very few major problems in terms of safe service return. So, we did do a lot of work to ensure that when the aircraft park, they were parked safely and that we believe they would return acceptably into service. But clearly this isn’t something we’ve done before. We don’t typically park aircraft and engines for 18 months. So, it would appear at the moment we’ve done good things. We are safely returning to service as we get more and more operators bringing aircraft back in.

MF: So, a real success in a very challenging situation.

AH: Yes. I think so, yes.

MF: Excellent. Alastair, could you tell us what superabsorbent polymer is?

AH: We use superabsorbent polymer in the into-plane refueling equipment, and it essentially does a very effective job of removing water to ensure we put dry, clean fuel onto the aircraft. Superabsorbent polymer itself is what you find in baby’s diapers. So, it does a great job of absorbing large amounts of water, essentially swelling when it absorbs. By doing so with it being constrained in a filtration element, it thereby stops the fuel flow. So, if you expose these SAP filters to a large amount of water, they can effectively hard-stop fuel flow at quite high pressure.

MF: So, from your perspective, what has been the technical problem with superabsorbent polymer?

AH: Jet fuel is one of the few things on an aircraft that has the source of being a common-mode failure. So, we have a single supply of fuel onboard the aircraft in the wings, and, clearly, if that fuel is contaminated, it has the potential to cause problems in both engines at the same time. Hence, if we’ve got problems with fuel quality as a result of superabsorbent polymer in the filters, it has the potential to hurt both engines, and we need to address that issue urgently from the safety perspective.

Superabsorbent polymer is a great technology. It’s protected the aircraft systems and engines very well over the last few years, and it does work very well, provided it's maintained and operated completely in accordance with the manufacturer’s instructions. However, in certain instances where those procedures aren’t followed properly or where maybe contaminated fuel is put through the systems, it can lead to some of that polymeric media migrating downstream into the aircraft and engine systems. The engine systems in particular are quite intolerant of this type of material, and it can cause fuel-system control problems.

MF: So, I understand as a result of that, the engine manufacturers, you included, have said that they want to move to an SAP-free world in the future.

AH: That’s right, and there’s a real urgency for the airlines to move away from this type of SAP technology as it does represent a safety risk, and the airlines are ultimately responsible for the quality of fuel that goes into the airframe. We, as engine manufacturers, have a zero-tolerance policy for superabsorbent polymer in fuel. So, fuel that is going into the aircraft that contains this polymeric material is not fit for purpose.

MF: So, Alastair, the industry is doing a huge amount of work trying to find alternative filtration technologies. What sort of feedback are you getting from your customers about that challenge, and what do they think about what’s going on?

AH: I think one of the big challenges, Mike, is the communication side. Some customers are very aware, but lots of customers aren’t as aware. I think it’s incumbent on us – and the rest of the industry – to work together in a collaborative way to ensure that everyone is aware of the risks and the challenges around using SAP media and the urgency to move to an alternative technology.

MF: Now, you in Rolls-Royce use thousands of sensors on your engines, and one of the new technologies in filtration uses a sensor to help protect against water contamination. Incidentally, the system is one that’s being implemented widely by Shell Aviation. What’s your view on the use of sensors in fueling systems?

AH: In our engine systems, we use many, many thousands of sensors to do different roles, and anything that can inhibit water coming onto the aircraft has got to be a great thing. So, recognising we move away from a SAP-type filtration system to a different system that might well need a water sensor. In traditional refueling, really the only sense you’d got was a Delta pressure gauge and a reliance on the operative doing the work to identify a problem. Now, if you’ve got water-sensing technology, maybe other technologies, it gives us information around fuel quality, fuel properties, then absolutely. That’d be a great thing, and potentially we have systems on the engine that can then react to those particular properties and attributes of the fuel going forward. That is certainly a possibility.

MF: It sounds like an exciting new development in the fueling world rather than just the engine world. Alastair, as the industry returns to normal operations, what is Rolls-Royce really focusing on in the new world?

AH: I think our prime focus at the moment really is around sustainability and the overall environmental impact of the aviation industry. From a jet fuel perspective, that’s really around sustainable aviation fuel, but sustainable aviation fuel really is only one of three main pillars of our environmental strategy. One is around more efficient engines, the other is around sustainable aviation fuel. The third is around hybrid electric and alternative solutions. But from a jet fuel perspective, certainly sustainable aviation fuel – or SAF as it’s known in the industry – is a really important topic that’s occupying a lot of time in Rolls-Royce, in terms of demonstrating product capability, working with the industry groups, and really trying to collaborate and bring through more availability in terms of sustainable fuel.

MF: Yes, but I guess it’s not something that Rolls-Royce can do on its own in a sense that it’s the whole industry that have got to work together. Are you running projects with different people? Are you trying to stimulate that sort of activity?

AH: You’re right. There’s no way that one individual company will fix this. There’s a massive challenge in terms of availability of product as we go out to 2050 in people’s net-zero targets. So, we’re working with a range of fueler companies, including Shell Aviation, who we have a memorandum understanding with at the moment in terms of technology development and all topics to do with sustainability.

MF: You mentioned earlier electric as an option. Where do you see electric solutions appearing? On engines or as a replacement for engine technology?

AH: I think if you look across the different sizes of aircraft, from urban air mobility with one or two people on board, to wide-body with 400 or 500 people on board, there’s a whole range of different solutions, and there isn’t a case of one size fits all. Hybrid electric could work in a smaller aircraft, and as you go through to a wide-body, large application, you’ll need large gas turbine engines – the type you can see here within Rolls-Royce. And in the middle, there’ll be some range of solutions, but we will definitely have more electrification in our product range going forward.

MF: Alastair, thank you very much for the conversation today.

AH: Thank you, Mike. It was an enjoyable conversation.

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